ES2308827T3 - VIBRATION ABSORBER FOR WIND TURBINES. - Google Patents

Abstract

The damper (40) and pendulum rod (3) pivot form a closed unit made up of one or more elastomer modules, possibly supplemented by additional mechanical or hydraulic dampers. The modules have distance disks to control their stiffness and are spread round the rod pivot point. The rod (3) itself should be flexible and possibly made up of elastomer components, using several rods and their pivots if so desired. The wind powerstation comprizes tower and machinery house (39) equipped with the rotor blades (35) and the damper load (1) should be arranged above the rod pivot, notably in the machine house (39).

Description

Vibration absorber for turbines wind power

The invention relates to an absorber of vibrations presented by the function of diminishing or equalizing vibrations that occur undesirably in constructions tower-like highs, particularly in turbine towers wind power

Tall towers like chimneys and the like they are often exposed to very high wind forces, so begin to vibrate corresponding to their characteristics of resonance. However, vibrations of larger amplitudes They are generally not desired.

The problem is particularly flagrant in wind turbines that frequently have high elongated towers  over 50 meters in which a machine room with large rotor blades, so along with the wind forces Different forces act on the entire construction. With turbines growing wind and towers, therefore, more and more high, towers or turbines are increasingly sensitive to vibrations

In turbines in the direct coastal zone (onshore / offshore) which, in addition to the wind forces, also they move by sea currents and waves, it is particularly importance a solution of vibration problems.

Wind turbines have partly machines with a variable number of revolutions, so the additional problem that the number of drive revolutions often passes through the natural frequencies of the tower, such so that large movements occur in the tower resonance manifestations

The indicated difficulties can be reduced or eliminate by the use of vibration absorbers according to the present invention. The use of absorbers vibrations according to the invention further causes that wind turbines with the usual construction sizes currently they can have a lower weight, which has as consequently a saving of material and, therefore, a construction  more economical

Additionally, the fatigue of materials that are produced by the movement of the tower has been decreased by the use of vibration absorbers in accordance with the invention and therefore the life of the towers has increased clearly. At the same time other components are also downloaded as the generator, the gears and not lastly, the blades of the rotor due to decreased movement, so that increases their useful life.

The towers have several natural frequencies, that manifest with different tower heights in the form of strong movements The first natural frequency of the tower is manifests in such a way that the tower bends from below towards above and the maximum deviation (vibration belly) has its maximum effect in the upper zone, that is, in the machine room that place on the tower (Figure 6). This natural vibration has the less frequently Additional natural vibrations with greater frequencies have one or several bellies of vibration, that is, sites where the tower has transverse movements. A Vibration form of this type is shown schematically in Figure 8.

Vibration absorbers have in the area of the greatest deviation of the tower the greatest effect and, so reasonable, in that place also fit a system of damping (for example, Figures 6, 8, 9). To absorb the First natural frequency, it is the upper area of the tower or the engine room. To absorb higher order frequencies is reasonable to couple the vibration absorber in the largest deviation of the tower that vibrates.

Absorbers with the most construction type simple, which are usually composed of a fixed vibration mass with a pendulum bar, a chain or a steel cable, they are known in principle from the state of the art (Figure 1), see, for example, the document WO-A-98/38392. Are used partially in towers and chimneys. However, so far I don't know have mounted vibration absorbers designed in a way corresponding in wind turbines. The turbine tower Current wind power is performed with a corresponding stiffness high, so that the stability of wind turbines is guarantees a relatively large use of material.

Since, however, the towers of wind turbines, to make maximum use of wind power, each are taller and also, for aesthetic reasons, more and more elongated, and the turbine itself, unlike, by way of example, Simple static chimneys, generated by rotor blades wind-driven active turning movements, which transmit centrifugal, rotational and other forces in part  complicated (particularly with imbalances always present, more or less intense) on total construction, where drive frequencies can be partially located at the natural frequencies of the components generally not dampened (if the drive frequency and the natural frequency in unbuffered systems are identical, this means the destruction of the turbine), the generation problem occurs or the heterogeneous decrease in vibrations despite the Modern materials currently available. Unlike the other elevated buildings, in fact, wind turbines are made up of two systems in vibration (tower, rotor) aligned in a way successive and mobile to each other that have both natural frequencies of similar magnitude, which in turn are close to the range of the frequencies produced by the operation of the turbine.

Therefore, the objective of develop new high-tech vibration absorbers that meet the requirements, particularly in wind turbines big. Such vibration absorbers, however, obviously they can also be used in other constructions raised and elongated, by way of example, in chimneys of ventilation of thermal power plants, incineration plants garbage, in high voltage masts, relay towers or in / on support pillars of elevated bridges or in the own ones bridges

It has now been observed that the absorbers of vibrations, which are essentially composed of mass of inertia, pendulum (bar / tube) and a damping unit can solve excellently in a given constructive arrangement the problems that have been listed above, particularly during use in large wind turbines with a frequency natural between 0.1 and 30 hertz. It has been shown that they are obtained particularly good results when the damping unit (40) is arranged in the pendulum bar (3) in the bearing area of pendulum or pendulum joint (4). Such absorbers of vibrations have advantages in a number of uses with respect to such absorbers in which the damping / spring elements they are applied directly to the mass of inertia (1) with the help of Tower walls (36) (Figure 1). Particularly such vibration absorbers have damping characteristics excellent unexpected wind turbines with their relationships of complex vibrations that have been described above. For the others have due to its compact construction with savings of space construction advantages over known absorbers Used for normal constructions. Since in turbines wind power, unlike tall chimneys or telegraphic masts high you have to drive a plurality of conduits of feed from the engine room by cross section usually very narrow tower, absorbers cushioned on a regular basis, whose damping means are in direct contact with the walls of the tower and, therefore therefore, they subtract a valuable space, they are barely suitable for such wind turbines.

Therefore, the object of the invention is a vibration absorber suitable for damping vibrations in wind turbines, which is essentially composed of mass of inertia, pendulum bar, bearing or articulation of pendulum and damping means, where the mass of inertia, the pendulum length and the strength of the damping means are adapt to the physical characteristics of the wind turbine of such so that the mass of inertia vibrates with phase shift in comparison with construction, which is characterized by the fact that damping means (40) form together with the articulation of pendulum (4) a closed unit in terms of construction and it they consist essentially of one or several, preferably four elastomeric modules (7), where the absorber can be accelerated by Any sense on a plane.

Damping by elastic elements also it is required to achieve higher natural pendulum frequencies of what would be the case with the default pendulum frequency by natural gravity. With higher frequencies> at approximately 1 Hz, otherwise the pendulum bar would be too short to be able to assume the dough (Figure 21).

The elasticity may show different rigidities in different directions in the plane of vibration of the mass, such that in the x direction, and different occur natural frequencies of the absorber. The stiffness of elastomers (7) can be regulated according to the invention by the use of separation discs (8) within the damping means.

The vibration absorber according to the invention may additionally possess elastomeric modules hydraulic or mechanical means (for example, shock absorbers spring) as known in the state of the art. Thus, also a subject of the invention is a vibration absorber corresponding that is characterized by comprising means of additional damping of hydraulic type (17) or mechanical type  (5), (6). Additional damping means are mounted preferably in terms of construction such that They require little space.

Such vibration absorbers are preferred in which the damping means (40) are composed essentially three to six elastomeric modules (7), which preferably arranged around the pendulum joint (4) and, in a given case, one or several hydraulic modules, where said hydraulic modules in preferred embodiments so various of the invention can be operated together with the components elastomeric passive, semi-active or active mode, that is, powered by external energy.

In addition, an absorber is an object of the invention. corresponding vibration, whose own pendulum bar (3) is elastic cushioning so that you can replace the damping unit (40) to some extent or may reinforce the same with an equal configuration, where they are particularly suitable such pendulums that are manufactured from components elastomeric or lattices of wire and / or plastic and, in one case given, that have a different elasticity coefficient in the sense x and y by, by way of example, different materials in the cross section and / or have an asymmetric profile. With such vibration absorbers can be absorbed at the same time Several frequencies in different senses.

In addition, absorbers are subject of the invention. of vibrations in which the mass of inertia (1) is composed of some embodiments of dough parts, such that the dough is can adapt correspondingly to the physical conditions of construction In other embodiments, a container serves as mass of inertia, which can accommodate different objects of diverse weight, for example, bulk product or its own components wind turbine.

Vibration absorbers according to the invention preferably comprise a hole perforation centrally arranged longitudinally (through mass of inertia, pendulum bar, damping element), which It allows, as an example, a cable passage.

Vibration absorbers according to The invention is preferably mounted on wind turbines, particularly in those with a natural frequency between 0.1 and 30 hertz, preferably between 0.2 and 10 hertz.

Surprisingly it has been observed that the damping characteristics of vibration absorbers with the type of construction according to the invention can be continue to improve, particularly with vibration ratios difficult and complex in construction that has to cushion, when the vibration absorber comprises several pendulum bars, preferably two to four, that carry the pendulum mass (1). An absorber of this type comprises two pendulum joints (4) for each pendulum bar (Figure 22). Elastic damping means may be present (40) in only one or both pendulum joints of each bar of pendulum. By the arrangement of several pendulum bars, the mass vibrates in the plane parallel to the suspension surface (parallel displacement).

Finally, turbines are the subject of the invention wind in which the vibration absorbers of according to the invention. Vibration absorbers, in preferred embodiments, can be applied inside the tower (35) below the engine room (39) or in the engine room machines outside the tower. The latter is mostly advantageous when the gondola or the engine room, what most  Of the times it is the case, it can rotate horizontally. In this case, the vibration absorber acts additionally with effect of damping or braking with respect to the rotational movement of The gondola

In a particular embodiment, the absorber of according to the invention it can also be mounted so "inverse" in the turbine, that is, the pendulum mass is situated above the support construction for the absorber no longer discontinued.

The wind turbines that are equipped with the vibration absorbers according to the invention, so Therefore, they work particularly without damaging the material and shape silent and therefore also contribute to less impact environmental.

The invention is described below with more detail:

The elements of the drawing have the following assignment and meaning

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The Figures represent the following:

Figure 1: tower vibration absorber, suspended with free vibration, spring (5) and damping (6) by tower wall support;

Figure 2: vibration absorber with unit damping (40) hooked on the tower;

Figure 3: vibration absorber with unit spring elastomeric damping (40) in the construction of support (37) and additional external (hydraulic) dampers (6), stiffness (5) of the adjustable pendulum joint;

Figure 4: vibration absorber with unit hydraulic elastomeric damping (passive);

Figure 5: Vibration absorber in the exterior of the tower (36) suspended in the gondola and rotating with azimuth;

Figure 6: wind turbine with vibrating tower (36) and vibration absorber arranged directly below from the engine room (39), belly up vibration (vibration of 1. order);

Figure 7: tower vibration absorber, mass of inertia (1) directed upwards;

Figure 8: wind turbine with vibrating tower (36) and vibration absorber in the belly of vibrations arranged in the tower (higher order vibration);

Figure 9: vibration absorber with unit damping consisting of a pendulum bar steel cable (44), fixed on the tower (36) inside the machine room (39);

Figure 10: damping unit (40) with elastomeric elements (7) and absorber support construction  (37) and through hole (38);

Figure 11: component damping bar elastomeric (ultra-type bearing) with high damping successively aligned (displaced);

Figure 12: tube absorber rod high-damping steel cable mesh (damping by friction);

Figure 13: vibration behavior of a non-damped system;

Figure 14: vibration behavior of a damped system;

Figure 15: vibration absorber in the room of machines (3) rotatably located, mass directed towards above, protruding from the gondola;

Figure 16: semi-active vibration absorber for the absorption of vibrations in the tower with unit of hydraulic elastomeric damping with control unit and electronic computer;

Figure 17: semi-active vibration absorber in a wind turbine for vibration absorption in the rotor and the tower with hydraulic elastomeric damping unit with control unit and electronic computer;

Figure 18: active vibration absorber with pump / compressor (22) in a wind turbine with unit hydraulic elastomeric damping with control unit and electronic computer;

Figure 19: passive damping elements and assets;

Figure 20: mode of action / operation of a Vibration absorber that works in a wind turbine.

Figure 21: natural frequency diagram of absorber in Hz with respect to pendulum length.

Figure 22: Damping element of a vibration absorber in a side and elevation view, which It comprises two pendulum bars with a total of four joints of elastic pendulum.

Vibration absorbers according to the invention preferably consist of a mass system of damped spring, which adjusts to the respective frequency of the tower and therefore vibrates with phase shift with Regarding the tower. The opposite vibration of the mass of the absorber Tower vibration decreases. Vibration absorbers They can be cushioned differently. If the absorber of vibrations were without damping, the natural vibration of the Tower would be virtually suppressed altogether. However, the two new typical vibration peaks that would occur in a damping system of this type would manifest themselves in a way negative about the vibration behavior of the tower. The Figures 13 and 14 show the transmission function of an absorber of vibrations not damped and one damped. By additional damping energy is removed from the system otherwise practically not buffered, so that both occur typical resonance manifestations that have been indicated without However, they are reduced by damping to such an extent that barely influences the vibration behavior of the tower.

The mass of inertia, the natural frequency and the degree of damping can be optimally adjusted according with the physical bases respectively present.

In order to balance the tolerances of masses, rigidities and natural frequencies, which are dispersed naturally during the manufacture of wind turbines, the Vibration absorbers can be manufactured in an adjustable way and can be adapted to the respective wind turbine. In total you can adjust the following quantities: mass, pendulum length, stiffness of elastic spring elements or having elastic cushioning, damping characteristics.

Vibration absorbers can be perform in several variants, which are indicated in part also in the Figures (see previous legends of the drawings).

The vibration absorber according to the invention can be fixed in principle with two variants in the construction and, in fact, as a pendulum absorber in the tower, suspended with spring free vibration and damping Optional additional support for the tower wall. Additionally it can be operated as a vibration absorber, that hooks on the tower with support construction (37) fixed on the tower wall or directly at the bottom in the machine room and whose pendulum has no contact with the wall of tower. This embodiment is preferred, particularly when space reasons contact with the wall of the tower.

According to the invention, the absorber of vibrations can also be fixed additionally on a hook, which also assumes part of the weight with a suspended construction. The Mass of absorber weight (1) can be fixed or adjustable. The mass of inertia (1) can be a bulk product container with Adjustable weight for hollow spaces that can be filled with Bulk product. It is possible to mix with each other even different bulk and / or liquid products or also introduce products into pieces The container can be produced from steel or plastic or concrete The weight adjustment capacity can be get for different volume weights of bulk products or also by the different degree of filling of the containers used. The weight may contain a recess in the area of the drivers located in the tower, for which the usual ascent So far in the tower is not endangered by the absorber. The mass of inertia can also be composed of individual masses of such that several discs can be stacked superimposed With a central perforation. The central hole is used for pendulum bar housing (3). The weight can be adjusted from this way for the quantity, thickness and material of the elements individual. As a complement to the load weights you can use additionally or alternatively components of the wind turbine as hydraulic groups and electrical devices as a damping mass. The height adjustment capacity (2) of the mass of inertia (1) and, therefore, the frequency adjustment of the vibration absorber is achieved by a threaded spindle, a string with elements that have to be suspended differently or continuously by cables adjustable by thimbles.

The pendulum mass can get, if it is necessary, a hole for the cable passage housing (38).

The power cable suspended freely in the upper area of the tower performs with an azimuthal movement a relative movement with respect to the tower and, therefore, with regarding the vibration absorber. When joining the absorber of vibrations at the height of the rotating power cable is necessary Pass the cable through the vibration absorber. For this, the vibration absorber, the suspension of the absorber and the Absorber bar holes are made.

With the use of a vibration absorber suspended vertically in the form of a pendulum, the force of Gravity plays an important role. If springs are not used additional, the natural frequency of the vibration absorber is determined by the force of gravity and, therefore, exclusively by the length of the absorber rod and the distribution of the pendulum weight on the absorber bar. For adjustment exact natural frequency, on the one hand you can modify the Pos 1 mass of the vibration absorber, on the other hand you can modify the length of the pendulum Pos 3.

By the use of spring elements additional the natural frequency of the absorber of vibrations by the length of the pendulum and additionally by the spring stiffness of the spring elements. For this arrangement can be determined freely the length of the pendulum. The length of the pendulum will include 0.1 m in such elements and 15 m. Particularly with frequencies greater than> 1 Hz can that system will be necessary, since otherwise the length of the Pendulum would be too short to place the necessary mass. The Springs are arranged between the vibration absorber and the tower. They can be joined between the tower wall and the mass or the tower wall and pendulum bar, above the mass as well as below the mass with the pendulum.

According to the invention, the term "spring" has to be considered in its broadest sense. Be include in this term all the constructive elements that can use preferentially due to its spring function and elastic. Therefore, the term spring comprises parts of according to the invention as spiral springs, bar bending, leaf springs, elastomers, steel cable springs and Similar.

To keep the two new frequencies that are produce as small as possible during the absorption function It is reasonable to dampen vibration absorbers. The figures 13, 14 show the difference in tower deviation with vibration absorber damped and not damped.

The vibration absorber can possess the same time damping and elastic functions. Both functions they can be done with two different components or with a individual component that contains both functions. The same they can be, for example, elastomeric components with corresponding damping characteristics, springs steel cable or even non-cushioned elastic springs together with additional buffers integrated or arranged separated. The elements can be arranged in different places between the mobile vibration absorber with respect to the tower and components attached to the tower, which perform the movement of tower vibration.

Preferably, vibration absorbers according to the invention they are operated independently of the tower wall, since no lateral fixings are required. The Global connection construction is integrated into the joint of pendulum. They can be operated suspended vertically, horizontal, located vertically and on all other axes from space. In this way there is the advantage that it is can be fixed anywhere and the absorption forces are transmit only at the point of suspension, that is, the absorber can be fixed in the machine room that rotates with with respect to the tower and at the same time it can be introduced in the stationary tower without contacting it. Without However, it can also be coupled with the wall of the tower.

The stiffness of the elastomer component (7) arranged in the upper pendulum joint can be configured  adjustable by variation of the distance of the elements rubber. The required length is varied by the stiffness adjustment of the pendulum so that the ideal pendulum length by the specific mass and the dimension of the tower can be performed practically regardless of the pendulum length otherwise predetermined by the force of gravity. He component consists of two elastomeric components (7) with cone shape with rotational symmetry tensioned together. The elastomeric components can also be realized spherical, convex or concave or even in the form of cylinders with central drilling The elastomeric material used has a large damping with a damping angle between 8º and 25º, preferably between 12º and 18º. The cardanic stiffness of elements depends on the distance between the conical elements. This distance and therefore stiffness increase by the inclusion of additional separation discs (8) or decrease by withdrawal or decrease of separation discs. For the passage of the cables of power, the pendulum bar (3), the inner part that connects to the pendulum bar and the separation discs can be Perform with a perforation. For the adjustment of different rigidities and, therefore, different natural frequencies in the x direction e y, elastomeric components can be made with windows (recesses in the elastomeric body) arranged so symmetric or asymmetric on the periphery of the bodies elastomeric

The damping required for the function of Absorption is applied by the elastomeric material used. So complementary or alternatively to this can be used additional hydraulic shock absorbers. They can be arranged separately, see Figures (3), (6) or even They can integrate into various elastomeric components. It is an advantage of this system that can be freely arranged suspended, that is to say, available without union with respect to the turntable tower in the engine room and therefore with a modification of the wind direction, the absorber fixed in the rotating machine room does not contact With the tower Additionally there is no movement relative in the torsional direction between the absorber of vibrations and wires. In this embodiment, the cable can be drive through the construction of the hollow absorber centrally or it can be passed laterally through the construction of the absorber. A further embodiment is possible by the use of a bar pendulum (Figure 11) elastic fixed on the gondola, which It consists of high cushioning material. It consists of several elastomer components aligned successively, tubular, in which a rubber layer (10) is included between two tubes with different diameters. They are configured according with Figure 11 such that the inner tube (11) and the tube external (12) are connected alternately, so that produces the deformation during the flexion of the bar that produced from this by the elastomer in the form of a movement  gimbal Elastomeric components can be made of cylindrical, conical and spherical shape (convex and concave).

The pendulum bar itself can be performed as a solid bar or even as a tube for housing The power cables. Like a cushioned pendulum bar it you can alternatively use a steel cable, which is composed of many longitudinal elements joined together (interlaced). Individual fibers can be made round, polygonal or flat. The damping of these elements is produced by friction between the cables. Alternatively you can include a buffer elastomer between the longitudinal elements of such so that impulse damping is performed on the element intermediate included.

For the accommodation of the cables you can lead the twisted wires (Figure 12) around a tube elastic (hose) that can accommodate cable ducts. By otherwise, cable ducts can be used as elements of support and damping. The pendulum length can be prolong by rigid elements.

Additionally, the pendulum bar can be produce from an asymmetric profile so that it present a different stiffness in the x and y direction, therefore They can absorb two different frequencies. It also can produce a corresponding effect by the use of materials different.

According to the invention you can also use dampened vibration absorbers hydraulics. For this, hydraulic dampers can be used in which the damping is applied by friction of liquid or even by friction by air. Additionally they are possible hydraulic elastomeric bearings as shown in Figure 4 (17) and Figure 19 (30). In these systems it is included in a displacement space (15) a hydraulic liquid (13) or gas. With a pendulum movement, the volume of the space of the displacement (15), so that the medium (13) is pumped to the inside or outside the scroll space. Now damping is achieved by driving the medium respectively by an adjustable or even adjusted regulating valve (16) of fixed form The medium is braked on the regulating valve, that is, energy is removed from the system. In this way, the pendulum experiences Adjustable damping The system may be built, as depicted in Figure 4, such that respectively two or even more elements are linked with a conduction. Alternatively, each element can be cushioned in a way individual together with a reservoir container, in which you can pump the excess liquid during the forcefulness of the spring and from which the missing volume can be removed again during release. This deposit container can be used even for several valves.

The number of the damping elements hydraulic can comprise from an element (together with a gimbal joint) up to about 10 elements, preferably 4 elements. The elements, to get equal stiffness and equal damping, can be distributed in symmetrical shape in all directions on the periphery of the absorber However, they can also be mounted asymmetrically to achieve different rigidities and different damping in the pendulum plane. This way they can be done in a targeted way  different natural frequencies in different directions of the pendulum plane x / y.

The elements can be included as depicted in Figure 4 in the upper area of the joint of pendulum. At the same time it is possible to introduce them, such as spring damping elements that have been described previously, anywhere between the stationary tower and the pendulum. Hydraulic damping elements can add by the elastomeric components (7) an additional stiffness to the system. Elastomeric components, however, are also they can set so soft that their stiffness has an influence not significant about the absorber system. Further, to achieve great rigidity, they can also tense each other two elastomeric bodies (7).

According to the invention you can also use semi-active hydraulic vibration absorbers. These absorbers are basically built as the absorbers that have been described above. The decisive difference is that throttle valves (16) can be controlled by a component electronic or by a mechanical device that is influenced by component vibrations. In this way, the damping can be adjust depending on the vibrations that occur in the tower and in the other components, such as the rotor blades. In the extreme case, the shock absorber can be joined by a regulation complete of the regulating valves (16) fixedly with the tower and can be released again at the right time with a cushioning adjusted so that it can address in a directed way a vibration that occurs. From this mode is able to counteract even vibrations that present with frequencies different from the adjusted frequency of absorber

In the semi-active absorber according to the invention, the regulating valve (16) is controlled electrically  depending on the vibrations in the tower, in the engine room or the shovels. You can control each valve so individual as combinations consisting of several or all of the valves The vibration signals are detected by detectors of acceleration (18), which are arranged in the critical components, and are send by cable or by station (23) and receiver (24) to the computer (19). The computer additionally detects the status of the pendulum by acceleration detectors (18) arranged in the pendulum in the directions of vibration decisive horizontals. The computer (19) transforms the signals of entry in orders with which it performs by the amplifier (20) the throttle control (16). With this system, the absorber can also counteract by directed regulation or opening of one or more regulating valves (16) even vibrations outside the tower. The vibrations that are produced in the tower can be better absorbed with the same mass of absorption with this system than with constant damping.

The new vibration absorbers of according to the invention with active damping possess particularly advantageous features. These absorbers they have a construction similar to semi-active absorbers that have been described above. The essential difference is that the pendulum can be moved by external energy introduced so additional. External energy can be supplied by a pump, a compressor or an engine. Active systems can be connect and disconnect randomly. There is additionally the possibility of activating, with the system disconnected, the passive or semi-active absorbers (for example, as emergency system). In the active absorber system you can arrange any number of active elements in the periphery. The active elements (Figure 18, (17)) can be arranged in the form of circle around the central axis of the pendulum or even in shape asymmetric The active elements can be arranged in any point between the main mass and the absorption mass. The minimum is an active element with additional pendulum articulation. The pendulum joint can be introduced as joint gimbal analogous to Figure 1, (4) or even as elastomeric element analogous to Figure 2, (4). The pendulum joint can also be integrated differently to Figure 18 in the active elements, so that it is not You need no additional pendulum suspension.

The pendulum can also be accelerated with greater intensity by the active components that the passive pendulum. From In this way, the pendulum mass can clearly decrease with force equal reaction. You can mount any number of active absorbers in a wind turbine.

Figure 20 shows the main function of a vibration absorber according to the invention during the Shovel vibration absorption. While the rotor blade (35) moves in the image plane to the left, the mass of absorption moves to the right, which provides the wind turbine tower as a reaction force a boost towards the left. With a correct temporary assignment with respect to the vibration of the rotor blade, it is quieted by this reason. The system can be used with vibrations in the plane of the rotor blade and peripheral direction. Obviously, from this mode also decreases the subsequent vibrations of the Pallas.

With an arrangement of the absorber in the exterior of the tower, as shown in Figure 5 for the passive absorber, movements of yaw (circular movements around the axis of the tower) of The gondola This is advantageous when connecting and stopping the azimuth drive. Also, with this active absorber suspended outside or standing can decrease the wind yaw movements caused by the wind, what which reduces the complexity of the azimuth drive and the brakes  azimuthal and the dimensioning of the other components of support.

The absorber can be arranged in any position (vertical, horizontal or any other axis of space) and it can be accelerated in any direction on a plane and so therefore, it can counteract all the vibrations that occur in the wind turbine. The hydraulic elastomeric bearing (actuator) it can have significant rigidity on its own as in the Figure 18 or contribute only in a subordinate way to stiffness of the total system. When the elements are activated actively of hydraulic damping that have been described so far, it They can use as actuators. Figure 19 shows several additional types of possible actuators, such as cylinder single-acting hydraulic (27), hydraulic cylinder double operation (28), hydraulic cylinder with reinforcement spring (18), hydraulically active elastomeric bearing (30), pneumatic spring (31), actuator with magnetic drive (32), actuator with motor drive (33), actuator with eccentric drive (34).

The absorber is activated by a pump (22) or a compressor or by electric adjustment elements direct. To be able to perform in a small hydraulic drive or a fast short movements compressor is suitable the use of deposits (Figure 18 (25)). Deposits are possible hydraulic (22) (Figure 18) or even gas tanks. The control and the regulation of the active elements are carried out with the control hydraulic (26). Alternatively a control can be used tire. Additional adjustment elements, see Figure 19 ((32), (33), (34)), are operated directly electrically.

The vibration absorber control of according to the invention is performed dependent on the vibrations that occur in the wind turbine. They can be measured directly at the generation site, for example, in the shovel (Figure 18, (18)). With the measurement on the blade you have to transmit the signal by collector rings or by radio. To avoid this complexity, vibrations can also be measured directly in the gondola. The known critical frequencies are they can filter on the computer from the signals and transform as the signals measured directly in corresponding signals for the absorber control, so that the absorber counteracts the disturbing vibrations that occur in the wind center. The absorber can simultaneously perform several frequencies in same and different axes of space. However, it can also address the different vibrations that are directed present with temporary displacement.

As already described above, the invention also comprises such absorbers comprising several  pendulum bars, in which the pendulum mass (1) is fixed. Preferably, such absorbers have two to four, particularly three pendulum bars. The pendulum bars do not they only include cardanic joints provided with means damping, which are fixed in the support construction (37, 52), which in a preferred embodiment joints corresponding even at its other end, where the mass (1). By this arrangement, the mass oscillates parallel with respect to to the address x / y. The stiffness of the pendulum bearing is composed of the sum of the stiffness of all joints. Also the second joint can comprise the damping means according to the invention (40), which are essentially composed of several elastomeric modules (7), preferably three to six and, in a given case, additional damping means that have been described above, hydraulic or even mechanical. The bars pendulum can also be joined with the second joint of pendulum above the pendulum mass with it. Too can be introduced, as drawn in Figure 22, in the mass of pendulum, pass through the pendulum mass or even apply on the outside of the pendulum mass in it.

Vibration absorbers with several pendulum bars are particularly suitable for mounting preferably on the back of the gondola and contribute to the effective decrease of horizontal vibrations, which are generated particularly for rotating rotor blades.

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References cited in the description

The list of references cited by the Applicant is solely for the convenience of the reader. No way part of the European patent document. While it has had great Be careful when compiling references, errors cannot be excluded or omissions and the EPO declines all responsibility in this regard.

Patent documents cited in the description

WO 9838392 A [0010]

Claims (12)

1. A vibration absorber suitable for vibration damping in wind turbines, consisting essentially of mass of inertia, pendulum bar, bearing or pendulum joint and damping means, where the mass of inertia, the length of the pendulum and the force of the damping means are adapted to the physical characteristics of the wind turbine in such a way that the mass of inertia vibrates with phase displacement compared to the construction, characterized in that the damping means (40) form together with the pendulum joint (4) a closed unit in terms of construction and consist essentially of one or several elastomeric modules (7), where the absorber can be accelerated in any direction in a plane. 2. The vibration absorber according to claim 1, characterized in that it comprises additional damping means of hydraulic type (17) or mechanical type (5), (6). The vibration absorber according to claim 1 or 2, characterized in that the elastomeric modules (7), for the regulation of their stiffness, comprise one or several separation discs (8). The vibration absorber according to one of claims 1 to 3, characterized in that the damping means (40) are composed of four elastomeric modules (7), which are distributed around the pendulum joint (4). 5. The vibration absorber according to one of claims 1 to 4, characterized in that the pendulum bar (3) itself is elastic. The vibration absorber according to claim 5, characterized in that the pendulum bar (3) is essentially composed of individual elastomeric components. The vibration absorber according to claim 5, characterized in that the pendulum bar (3) is essentially composed of an interlaced steel cable or a framework of tubular steel cable. The vibration absorber according to one of claims 1 to 7, characterized in that the mass of inertia (1) is fixed in several pendulum bars (3) with several of said pendulum joints (4) and several of said damping means (40). 9. A wind turbine consisting essentially of a tower (36) and a machine room (39) in and on which drive means and rotor blades (35) are arranged, characterized in that it comprises a vibration absorber in accordance with the claims 1-8. The wind turbine according to claim 9, characterized in that the vibration absorber is applied to the pendulum joint (4) with freedom of movement in the support construction (37) without additional connection with respect to the tower or the machine room. 11. The wind turbine according to claim 9 or 10, characterized in that the vibration absorber is arranged such that its mass of inertia (1) is located above the pendulum joint (4). 12. The wind turbine according to one of claims 9 to 11, characterized in that said vibration absorber is arranged outside the tower in or on said machine room (39).